Manufacturing hydrocarbon fluids

ABSTRACT

A system and methods for manufacturing a base stock from a light hydrocarbon stream. An exemplary method includes cracking the light hydrocarbon stream to form a raw product stream. Water is removed from the raw product stream to form an oligomerization feed stream. The oligomerization feed stream is oligomerized to form an intermediate stream. A heavy olefinic stream is distilled from the intermediate stream. The heavy olefinic stream is hydro-processed to form a hydro-processed stream. The hydro-processed stream is distilled to form the base stock.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/721,238, filed on Aug. 22, 2018, the entire contents of which areincorporated herein by reference.

FIELD

The techniques described herein provide systems and methods formanufacturing a hydrocarbon fluids from a light hydrocarbon stream. Thelight hydrocarbon stream is processed in to generate a mixture ofcompounds that are oligomerized and hydro-processed to form thehydrocarbon fluids.

BACKGROUND

This section is intended to introduce various aspects of the art, whichmay be associated with exemplary embodiments of the present techniques.This description is believed to assist in providing a framework tofacilitate a better understanding of particular aspects of the presenttechniques. Accordingly, it should be understood that this sectionshould be read in this light, and not necessarily as admissions of priorart.

High molecular weight paraffins suitable for the production of highquality hydrocarbon fluids and distillate fuel may be in short supply orexpensive to manufacture. In addition, the oligomerization of olefins istypically performed with high purity feed streams, such as polymer gradeethylene. For example, the production of hydrocarbon fluids from lighthydrocarbon streams may involve numerous steps, which affect the costsfor the final products. One example of the production of these compoundsis the production of syngas, CO and H₂ by reforming, followed byFischer-Tropsch reactions which preferentially synthesize linear highmolecular weight products.

Some previous research activities have focused on using impure ethylenefeeds to produce polyalphaolefins (PAOs). For example, U.S. PatentApplication Publication No. 2010/0249474 by Nicholas et al. discloses a“process for oligomerizing dilute ethylene.” As described in thepublication, a fluid catalytic process (FCC) may provide a diluteethylene stream, as heavier hydrocarbons are processed. The ethylene inthe dilute ethylene stream may be oligomerized using a catalyst, such asan amorphous silica-alumina base with a Group VIII or VIB metal that isresistant to feed impurities such as hydrogen sulfide, carbon oxides,hydrogen and ammonia. About 40 wt. %, or greater, of the ethylene in thedilute ethylene stream can be converted to heavier hydrocarbons.

Further, U.S. Patent Application Publication No. 2014/0275669 by Daageet al. discloses the “production of lubricant base oils from diluteethylene feeds.” As described in this publication, a dilute ethylenefeed, for example, formed while cracking heavier hydrocarbons, may beoligomerized to form oligomers for use as fuels or lubricant base oils.The oligomerization of the impure dilute ethylene is performed with azeolitic catalyst. The zeolitic catalyst is resistant to the presence ofpoisons such as sulfur and nitrogen in the ethylene feed. Diluents suchas light paraffins, may be present without interfering with the process.

The feed used for both processes described above may be derived from theprocessing of oil in a fluid catalytic cracker (FCC). In an FCC, heavierhydrocarbons, such as crude oil fractions with a molecular weight ofabout 200 to about 600, or higher, are contacted with a catalyst at hightemperatures to form lower molecular weight compounds. The byproductgases from the FCC include olefins that may be used to form theoligomers.

SUMMARY

In an embodiment, the present invention provides a system formanufacturing a base stock from a light hydrocarbon stream. The systemincludes a cracker configured to form a raw product stream from thelight hydrocarbon stream, a separator configured to remove water fromthe raw product stream forming an oligomerization feed stream, and anoligomerization reactor configured to increase a molecular weight of theoligomerization feed stream forming a raw oligomer stream. The systemfurther includes a distillation column configured to separate a heavyolefinic stream from the raw oligomer stream and a hydro-processingreactor configured to hydro-process the heavy olefinic stream to form ahydro-processed stream. A product distillation column is configured toseparate the hydro-processed stream to form the base stock.

In another embodiment, the present invention discloses a method formanufacturing a base stock from a light hydrocarbon stream. The methodincludes cracking the light hydrocarbon stream to form a raw productstream, removing water from the raw product stream to form anoligomerization feed stream, and oligomerizing the oligomerization feedstream to form an intermediate stream. A heavy olefinic stream isdistilled from the intermediate stream, and the heavy olefinic stream ishydro-processed to form a hydro-processed stream. The hydro-processedstream is distilled to form the base stock.

In another embodiment, the present invention provides a system formanufacturing a base oil stock from a light hydrocarbon stream. Thesystem includes a steam cracker to form a raw product stream from thelight hydrocarbon stream. A separator is configured to remove naphtha,water, steam cracker gas oil (SCGO), and tar from the raw product streamto form an oligomerization feed stream. An oligomerization reactor isconfigured to convert the oligomerization feed stream to a highermolecular weight stream by contacting the oligomerization feed streamwith a heterogeneous catalyst. A distillation column is configured toseparate a heavy olefinic stream from the higher molecular weightstream. The distillation column is configured to recover a lightalpha-olefin stream from the higher molecular weight stream. Ahydro-processing reactor is configured to demetallate the heavy olefinicstream, to crack the heavy olefinic stream, to form isomers in the heavyolefinic stream, or to hydrogenate olefinic bonds in the heavy olefinicstream, or any combinations thereof. A product distillation column isconfigured to separate the isomers in the heavy olefinic stream to forma plurality of base stock streams.

DESCRIPTION OF THE DRAWINGS

The advantages of the present techniques are better understood byreferring to the following detailed description and the attacheddrawings.

FIG. 1 is a simplified block diagram of a system for producinghydrocarbon fluids from a light gas feed, in accordance with examples.

FIG. 2 is a process flow diagram of a method for producing hydrocarbonfluids from a light hydrocarbon stream, in accordance with examples.

FIG. 3 is a plot of the yield of different weight molecules, showing thechanges as the catalyst is changed, in accordance with examples.

FIG. 4 is a plot of a simulated distillation by gas chromatographycomparing the products for a gas feed with hydrogen to a gas feedwithout hydrogen, in accordance with examples.

FIGS. 5(A) and 5(B) are plots of C-13 NMR spectra comparing a testproduct to a hydrocarbon fluid.

FIGS. 6(A) to 6(C) are 1-H NMR spectra comparing test products to aGroup II hydrocarbon base stock.

DETAILED DESCRIPTION

In the following detailed description section, specific embodiments ofthe present techniques are described. However, to the extent that thefollowing description is specific to a particular embodiment or aparticular use of the present techniques, this is intended to be forexemplary purposes only and simply provides a description of theexemplary embodiments. Accordingly, the techniques are not limited tothe specific examples described below, but rather, include allalternatives, modifications, and equivalents falling within the truespirit and scope of the appended claims.

Recent improvements in the production of hydrocarbons, for example, theuse of hydraulic fracturing and tertiary oil recovery techniques, haveresulted in the increased availability of lower molecular weighthydrocarbons, termed light hydrocarbon streams herein. These includenatural gas and natural gas liquids (NGL), which may include methane,ethane, propane, and butane, along with other hydrocarbon and heteroatomcontaminants. The use of the lower molecular weight hydrocarbons asfeedstocks for chemical processes may provide economic benefits.However, upgrading the lower molecular weight feedstocks to increase themolecular weight may pose challenges.

The techniques described herein disclose a method for producing highmolecular weight molecules from a raw olefin stream that may includeolefins, paraffins, hydrogen, and carbon monoxide. The raw olefin streamis provided by a steam cracking reactor, or cracker, which may becontrolled to provide a higher molecular weight feed stock from a lighthydrocarbon stream. The light hydrocarbon stream has an API gravity ofat least 45, at least 50, at least 55, at least 60, at least 65, or atleast 70 according to various embodiments of the present invention.Further, the hydrogen content of the starting raw hydrocarbons may begreater than or equal to 14%, or, in some examples, greater or equal to16%. In some examples, the light hydrocarbon stream may also includecompounds having two to four, two to six, two to 12, or two to 20, ormore, carbon atoms. In some examples, the feed is a natural gas liquids(NGL) stream. In other examples, the feed includes methane, ethane,propane, or butane. In some examples, the light hydrocarbon feedstockhas an API gravity of between about 45 and 55 and includes moleculeswith carbon chains of about two to 25 carbon atoms in length, amongothers. In other examples, the light hydrocarbon feedstock has an APIgravity of between about 55 and 65 and includes molecules with about twoto 10 carbon atoms, among others. In other examples, the lighthydrocarbon feedstock has an API gravity of between about 55 and 65 andincludes molecules with about two to 10 carbon atoms, among others. Inyet other examples, the light hydrocarbon feedstock has an API gravityof between about 65 and 75 and includes molecules with about two to fivecarbon atoms, among others.

The light hydrocarbon stream may be sourced from any number ofhydrocarbon formations, including, for example, tight gas formations.These may include the Clinton, Medina, and Tuscarora formations inAppalachia, the Berea sandstone in Michigan, the Bossier, Cotton Valley,Olmos, Vicksburg, and Wilcox Lobo formations along the Gulf Coast, theGranite Wash and Atoka formations in the Midcontinent, the Canyonformation and other formations, in the Permian Basin, and the Mesaverdeand Niobrara formations in multiple Rocky Mountain basins. Any number ofother formations may be used to provide the light hydrocarbon stream,such as the Rotliegend Group of formations in Germany and theNetherlands, the Eagle Ford group in Texas, and the Bakken formations inMontana, North Dakota, Saskatchewan, and Manitoba.

As used herein “cracking” is a process that uses decomposition andmolecular recombination of organic compounds to produce a greater numberof molecules than were initially present. In cracking, a series ofreactions take place accompanied by a transfer of hydrogen atoms betweenmolecules. Cracking may be performed in a thermal cracking process, asteam cracking process, a catalytic cracking process, or a hydrocrackingprocess, among others. For example, naphtha, a hydrocarbon mixture thatis generally a liquid having molecules with about five to about twelvecarbon atoms, may undergo a thermal cracking reaction to form ethyleneand Hz among other molecules. In some examples, the free radicals formedduring the cracking process may form compounds that are more complexthan those in the feed.

A separation train after a steam cracker may include over a dozen stepsand pieces of equipment to produce high purity polymer grade ethylene.In addition, the raw product stream may be compressed from about 10 psigto about 550 psig before entering a cold box to remove H₂, CO, and CH₄impurities. Decreasing the process pressure greatly reduces the cost ofseparation and thus the overall process. An exemplary simple separationmay include a primary fractionator, a caustic tower, a drier, and anacetylene converter. Further, the raw product stream may be compressedto only about 250 psig to implement the simple separation, loweringcosts over compression to 550 psig. The elimination of the remainingback-end separation train decreases the cost of production, but producesan impure olefin stream that can be processed by the impure olefinstream conversion process to produce higher molecular weight products.

To avoid the need for separation, the techniques use poison tolerantheterogeneous catalysts, such as zeolites, that are capable of olefinoligomerization in the presence of hydrogen and carbon monoxide. Theproducts include hydrocarbon fluids, such as gasoline, diesel, andlubricant range linear and isoparaffins, in addition to highly branchedmolecules useful for chemical applications, such as base stocks.

As used herein, “hydrocarbon fluids” refers to isoparaffinichydrocarbons in a naphtha and distillate range of molecular weights.Lightly or highly branched paraffinic molecules are useful ashydrocarbon fluids or transportation fuels. Hydrocarbon fluids mayinclude hydrocarbon fluids used for forming lubricants. As used herein,“base stock” or “base oil stock” refers to hydrocarbons in a lubricantrange of molecular weights. Lightly or highly branched molecules oflower molecular weights are useful as hydrocarbon fluids ortransportation fuels. Group I hydrocarbon fluids or base oils aredefined as base oils with less than 90 wt. % saturated molecules and/orat least 0.03 wt. % sulfur content. Group I hydrocarbon fluids also havea viscosity index (VI) of at least 80 but less than 120. Group IIhydrocarbon fluids or base oils contain at least 90 wt. % saturatedmolecules and less than 0.03 wt. % sulfur. Group II hydrocarbon fluidsalso have a viscosity index of at least 80 but less than 120. Group IIIhydrocarbon fluids or base oils contain at least 90 wt. % saturatedmolecules and less than 0.03 wt. % sulfur, with a viscosity index of atleast 120.

Further, the hydrocarbon fluids may be referred to as light neutral(LN), medium neutral (MN), and heavy neutral (HN), for example, asdetermined by viscosity. The term “neutral” generally indicates theremoval of most nitrogen and sulfur atoms to lower reactivity in thefinal oil. The hydrocarbon fluids are generally classified by viscosity,measured at 40° C. as a kinematic viscosity under the techniquesdescribed in ASTM D445. The viscosity may be reported inmillimeters{circumflex over ( )}2/second (centistokes, cSt). Thehydrocarbon fluids may also be classified by boiling point range, forexample, determined by simulated distillation on a gas chromatograph,under the techniques described in ASTM D 2887. It should be noted thatthe viscosity ranges and boiling point ranges described herein aremerely examples, and may change, depending on the content of linearparaffins, branched paraffins, cyclic hydrocarbons, and the like A lightneutral base stock may have a kinematic viscosity of about 4 cSt toabout 6 cSt and may have a boiling point range of about 380° C. to about450° C. A medium neutral base stock may have a kinematic viscosity ofabout 6 cSt to about 10 cSt and a boiling point range of about 440° C.to about 480° C. A heavy neutral base stock may have a kinematicviscosity of about 10 cSt to about 20 cSt, or higher, and a boilingpoint range of about 450° C. to about 565° C.

As used herein, a “catalyst” is a material that increases the rate ofspecific chemical reactions under certain conditions of temperature andpressure. Catalysts may be heterogeneous, homogenous, and supported. Aheterogeneous catalyst is a catalyst that has a different phase from thereactants. The phase difference may be in the form of a solid catalystwith liquid or gaseous reactants or in the form of immiscible phases,such as an aqueous acidic catalyst suspended in droplets in an organicphase holding the reactants. A heterogeneous catalyst may be bound, suchas a zeolite bound with alumina or another metal oxide. A homogeneouscatalyst is soluble in the same phase as the reactants, such as anorganometallic catalyst dissolved in an organic solvent with a reactant.

In an example of a process to convert light gas to high qualityhydrocarbons and base oil stocks, for example, using the system andmethod of FIGS. 1 and 2, a light hydrocarbon stream, that may includeethane, is converted, via steam cracking, to an impure olefinic streamor raw product stream. The raw product stream is then sent to a quenchfractionator where naphtha, water, steam cracking gas oil, and tar areseparated out to form an oligomerization feed stream. Theoligomerization feed stream may contain ethylene, propylene, acetylene,propyne, hydrogen, carbon monoxide, methane, ethane, propane, hydrogendisulfide, carbon monoxide, and water. Additional impurities in the ppblevel such as Hg, PH₃, AsH₃, COS, and NO_(x) may also be contained inthe stream.

The oligomerization feed stream may be processed by a caustic tower toremove H₂S and CO₂ as well as a drier to remove excess water. As usedherein, a “caustic tower” is a separation tower in which a causticsolution, such as an aqueous solution of sodium hydroxide, is contactedwith a hydrocarbon stream to remove some heteroatom impurities, such assulfur compounds and carbon dioxide. The caustic tower may use anynumber of internal flow arrangements, such as co-current flows andcounter-current flows, among others. Other units, such as settlers, maybe used with the caustic tower to separate the hydrocarbon from thecaustic solution.

The oligomerization feed stream then enters the oligomerization process,which converts the olefins in the oligomerization feed stream to highermolecular weight products. The conversion may be performed in a numberof different reactor types including but not limited to a fixed bed, aslurry-bubble column, a CSTR, or a moving bed. As described herein, aheterogeneous catalyst may be used, for example, taking the form ofextrudates or small spheres or particles. The space velocity over thecatalyst could range from about 0.05 to about 50 WHSV depending on thedesired product composition. The higher molecular weight productscontaining gasoline, diesel, and base stock can be separated. Thesematerials may be used as is, or may be hydro-processed, as describedherein. For example, they may be hydrotreated to remove heteroatoms andsaturate olefins. The process conditions and catalyst for thehydro-processing of paraffins and isoparaffins are known in the art.

For ease of reference, certain terms used in this application and theirmeanings as used herein are set forth. To the extent a term is notdefined herein, it should be given the broadest definition persons inthe pertinent art have given that term as reflected in at least oneprinted publication or issued patent. Further, the present techniquesare not limited by the usage of the terms shown herein, as allequivalents, synonyms, new developments, and terms or techniques thatserve the same or a similar purpose are considered to be within thescope of the present claims.

FIG. 1 is a simplified block diagram of a system 100 for producinghydrocarbon fluids from a light gas feed, in accordance with examples.The process begins with the introduction of a hydrocarbon feed stream,such as a light hydrocarbon stream 102, to a steam cracker 104. As usedherein, a hydrocarbon feed stream may include a composition prior to anytreatment, such treatment including cleaning, dehydration or scrubbing,as well as any composition having been partly, substantially or whollytreated for the reduction or removal of one or more compounds orsubstances, including, but not limited to, sulphur, sulphur compounds,carbon dioxide, water, mercury, and one or more C2+ hydrocarbons, suchas ethane, propane, butane, and the like.

Steam Cracking

In the steam cracker 104, the light hydrocarbon stream 104 is dilutedwith steam, and then briefly heated to high temperatures in a steamcracker, such as above 800° C., before the reaction is quenched. Thereaction time may be milliseconds in length. Oxygen is excluded toprevent degradation and decrease the formation of carbon oxides. Themixture of products in the raw product stream 106 from the steam cracker104 may be controlled by the feedstock, with the lighter feedstocks ofthe light hydrocarbon stream 102, such as ethane, propane, or butane, orcombinations thereof, among others, favoring the formation of lighterproducts, such as ethylene, propylene, or butadiene, among others. Theproduct distribution in the raw product stream 106 may also becontrolled by the steam/hydrocarbon ratio, the reaction temperature, andthe reaction time, among other factors.

A separator 108 may be used to separate the water formed from the steamand degradation products, from the raw product stream 106 to form anoligomerization feed stream 110. The separator 108 may include a flashtank to allow water to condense and settle, while product gases flowout, forming the oligomerization feed stream 110. In some examples,chiller systems may be used to condense the water from the raw productstream 106.

After water removal, the oligomerization feed stream 110 may include,for example, approximately 5% to 90% olefin (ethylene, propylene,butylene, and the like), 5% to 80% hydrogen, 0 to 20% alkyne (acetylene,propyne, and the like), 0% to 50% paraffin (methane, ethane, C3+), 10 to10,000 wt. ppm of carbon monoxide, and trace water. In some examples,the oligomerization feed stream 110 includes 35% to 55% olefin, 30% to60% hydrogen, 0.5% to 3% alkyne, 5% to 30% paraffin, and 500 to 2,000wt. ppm of carbon monoxide.

Oligomerization

The oligomerization feed stream 110 is provided to an oligomerizationreactor 112, where it is contacted with a zeolite catalyst 114. Thezeolite catalyst 114 is generally a poison tolerant and regenerablecatalytic zeolite capable of the oligomerization of impure and diluteolefins to C10+ products or C25+ to produce diesel, lube, andhydrocarbon fluid molecules. The zeolites suitable for this conversioninclude, but are not limited to, 10-ring zeolites such as ZSM-5 (MFI),ZSM-11 (MEL), ZSM-48 (MRE), and the like, with Si/Al₂ ratios from 5 to500. The zeolites are used in their proton form and may or may not bepromoted with metals by ion exchange or impregnation. In addition, thebinder used during formulation be used to control the to yield andproduct slate.

The oligomerization process can be performed as a single step process ora two-step process. In a single step process, the oligomerizationreactor 112 performs the oligomerization in a single stage or in asingle reactor in. The oligomerization feed stream 110 is introducedinto the single stage as a gas phase feed. The oligomerization feedstream 110 is contacted with the zeolite catalyst 114 under effectiveoligomerization conditions. For example, the ethylene feed can becontacted with the zeolite catalyst at a temperature of 20° C. to 300°C., such as at least 25° C. or at least 50° C. or at least 100° C. and250° C. or less, or 225° C. or less. The ethylene feed can be contactedwith the catalyst at a gas hourly space velocity, based on ethylene, of1 hr⁻¹ to 500 hr⁻¹, such as at least 5 hr⁻¹ or at least 10 hr⁻¹ or atleast 20 hr⁻¹ or at least 30 hr⁻¹ and 250 hr⁻¹ or less or 100 hr⁻¹ orless. The total pressure can be from 1 atm (100 kPa) to 200 atm (20.2MPa), and about 100 atm (10.1 MPa) or less. Optionally, theoligomerization feed is contacted with the catalyst at a hydrogenpartial pressure that is at least 1% of the total pressure, such as atleast 5% of the total pressure at least 10% of the total pressure, or upto 50% of the total feed on a volumetric basis. The reaction forms a rawoligomer stream 116 that can then be fractionated in a distillationcolumn 118.

In a two-step process, a first oligomerization to C6+ olefins, forexample, C6 and higher carbon number oligomers, is achieved under gasphase conditions similar to those described above. The product is thencondensed to recover the C6+ olefins or to recover C10+ olefins, such asC10 and higher carbon number oligomers. Recovering the C6+ olefinsroughly corresponds to recovering an intermediate portion from the firstoligomerization having a boiling point of 60° C. or greater. Recoveringthe C10+ olefins roughly corresponds to recovering an intermediateportion with a boiling point of at least 170° C.

Accordingly, the intermediate product that is recovered for furtheroligomerization can correspond to an intermediate product with aninitial boiling point of at least 60° C., such as at least 100° C., orat least 150° C. The resulting intermediate product is then furtheroligomerized in presence of an acid catalyst under liquid phaseconditions to produce higher molecular weight molecules, such as withmore than 20 carbons atoms (C20+), or with more than 26 carbon atoms(C26 +). For the liquid phase oligomerization, the olefin-containingfeed from the first stage can be contacted with the catalyst at atemperature from 20° C. to 300° C., such as at least 25° C., or at least50° C., or at least 100° C., 250° C. or less, or 225° C. or less. Thetotal pressure can be from 1 atm (100 kPag) to 200 atm (20.2 MPag), or100 atm (10.1 MPag) or less. In some examples, the liquidoligomerization feed can be contacted with the catalyst at a hydrogenpartial pressure that is at least 1% of the total pressure, such as atleast 5% of the total pressure or at least 10% of the total pressure.

The oligomerization reactor 112 may use a recycle loop to allow lowermolecular weight oligomers to be recycled to the cracker 104, or to beprovided to other reaction systems, such as a dimerization or alkylationunit, to increase the yield of products. For example, in a single stepoligomerization process, the oligomers formed during oligomerization maybe roughly divided into three types of compounds. A first type ofcompounds, termed a light olefinic stream 120, corresponds to compoundshaving about 10 carbon atoms or less. Such compounds correspond tonaphtha boiling range compounds. Due to the lower value of naphtharelative to lubricant base oils, a portion of the naphtha boiling rangecompounds can optionally be recycled to the steam cracker 104 in orderto increase the yield of the oligomerization feed stream 110. This canallow the naphtha boiling range compounds to be recycled and convertedinto higher value products. In some examples, lower molecular weightlinear alpha-olefins, e.g., with less than about 10 carbon atoms, may berecovered from the light olefinic stream 120 as a product stream, forexample, for polymerization processes.

A second group of compounds, termed an intermediate olefinic stream 122,may have between about 10 and about 25 carbon atoms. These compounds maycorrespond to distillate fuel compounds, such as diesel or kerosene, andinclude other olefinic compounds. As for the light olefinic stream 120,the intermediate olefinic stream 122 may be partially, or fully,recycled to the cracker 104 to increase the yield of the oligomerizationfeed stream 110. Further, the intermediate olefinic stream 122 may beused as a feedstock for other processes, such as dimerization oralkylation. In some examples, the intermediate olefinic stream 122 maybe combined into other streams prior to final product separation, asdescribed herein.

The third group of compounds, termed a heavy olefinic stream 124, mayhave at least about 24 carbon atoms. It may be noted that the olefinicstreams 120, 122, and 124 may not be composed of 100% olefiniccompounds, but may include a number of other compounds, such asparaffin, that are removed in the same boiling point ranges as theolefinic compounds. For example, the light olefinic stream 120 mayinclude, for example, linear alpha-olefins having from about four carbonatoms to about 10 carbon atoms and unreacted ethylene. Further, ashigher molecular weight compounds are formed, the amounts of paraffiniccompounds may increase as well. These compounds may correspond tolubricant boiling range compounds. To lower the amounts of contaminants,as well as to upgrade the final products, the heavy olefinic stream 124may be provided to a hydro-processing reactor 126. It may be noted thatthe olefinic streams 120, 122, and 124 may not be pure olefins, but mayinclude other compounds with similar boiling points, such as paraffiniccompounds. The paraffin content often increases with the molecularweight.

Various types of hydro-processing can be used in the production ofhydrocarbon fluids, such as fuels, naphtha's, and base stocks. Forexample, a catalytic dewaxing, or hydrocracking/hydroisomerization(HDC/HDI) process, may be included to modify viscosity properties orcold flow properties, such as pour point and cloud point. Thehydrocracked or dewaxed feed can then be hydrofinished, for example, tosaturate olefins and aromatics from the olefinic streams 120, 122, and124.

Hydro-Processing

As used herein, “hydro-processing” includes any hydrocarbon processingthat is performed in the presence of hydrogen, such as hydroconversion,hydrocracking, hydrogenation, hydrotreating, hydrodesulfurization,hydrodenitrogenation, hydrodemetallation, and hydroisomerization, amongothers. The hydrogen may be added to the hydro-processing reactor 126 asa hydrogen treat stream 128. The hydrogen may be added to thehydro-processing reactor 126 as one or more hydrogen treat streams 128.The products of the hydro-processing reactor 126, termed ahydro-processed stream 130, may have lower contaminants, includingmetals and heteroatom compounds, as well as improved viscosities,viscosity indices, saturates content, low temperature properties,volatilities and depolarization, and the like.

The products of the hydro-processing reactor 126, termed ahydro-processed stream 130, may have lower contaminants, includingmetals and heteroatom compounds, as well as improved viscosities,viscosity indices, saturates content, low temperature properties,volatilities and depolarization, and the like.

After forming compounds by oligomerization, and separating out the lightolefinic stream 120 and the intermediate olefinic stream 122, the heavyolefinic stream 124 may be provided to the hydro-processing reactor 126to remove contaminants and improve product properties, such as cold flowproperties. In an example, the intermediate olefinic stream 122 may beblended with the heavy olefinic stream 124 and sent to thehydro-processing reactor 126. For example, hydrotreatment or mildhydrocracking can be used for removal of contaminants, and optionally toprovide some viscosity index uplift, while hydroisomerization andhydrocracking, termed catalytic HDC/HDI, may be used to improve coldflow properties.

In the discussion below, a stage in a hydro-processing reactor 126 cancorrespond to a single reactor or a plurality of reactors. In someexamples, multiple reactors can be used to perform one or more of theprocesses, or multiple parallel reactors can be used for all processesin a stage. Each stage or reactor may include one or more catalyst bedscontaining hydro-processing catalyst. Note that a catalyst bed in thediscussion below may refer to a partial physical catalyst bed. Forexample, a catalyst bed within a reactor could be filled partially witha hydrocracking catalyst and partially with an HDC/HDI catalyst. Forconvenience in description, even though the two catalysts may be stackedtogether in a single catalyst bed, the hydrocracking catalyst and theHDC/HDI catalyst can each be referred to conceptually as separatecatalyst beds.

In the discussion herein, the hydro-processing reactor 126 may includethe one or more stages, such as two stages or reactors and an optionalintermediate separator, that are used to contact a feed with a number ofcatalysts under hydro-processing conditions. The catalysts can bedistributed between the stages or reactors in any convenient manner. Thehydrogen treat stream 128 may be added to each of the stages or reactorsseparately, or may be added in fewer additions, such as to each reactor,or only a first reactor.

Various types of hydro-processing can be used in the production of fuelsand/or lubricant base oils. Typical processes include a catalyticdewaxing, or hydrocracking/hydroisomerization (HDC/HDI) process, tomodify viscosity properties or cold flow properties, such as pour pointand cloud point. The hydrocracked or dewaxed feed can then behydrofinished, for example, to saturate olefins and aromatics from thehydro-processed stream 130. In addition to the above, a hydrotreatmentstage can also be used for contaminant removal. The hydrotreatment ofthe oligomer feed to remove contaminants may be performed prior to orafter the hydrocracking or the HDC/HDI.

Hydroisomerization/Hydrocracking (HDC/HDI)

Suitable HDC/HDI (dewaxing) catalysts may include molecular sieves suchas crystalline aluminosilicates, or zeolites. In an example, themolecular sieve may be ZSM-5, ZSM-22, ZSM-23, ZSM-35, ZSM-48, or zeoliteBeta, or may be any combinations thereof, such as ZSM-23 and ZSM-48, orZSM-48 and zeolite Beta. Molecular sieves that are selective fordewaxing by isomerization, as opposed to cracking, may be used, such asZSM-48, zeolite Beta, ZSM-23, or any combinations thereof. The molecularsieves may include a 10-member ring 1-D molecular sieve. Examplesinclude EU-1, ZSM-35 (or ferrierite), ZSM-11, ZSM-57, NU-87, SAPO-11,ZSM-48, ZSM-23, and ZSM-22. Some of these materials may be moreefficient, such as EU-2, EU-11, ZBM-30, ZSM-48, or ZSM-23. Note that azeolite having the ZSM-23 structure with a silica to alumina ratio offrom 20:1 to 40:1 may be referred to as SSZ-32. Other molecular sievesthat are isostructural with the above materials include Theta-I, NU-10,EU-13, KZ-1, and NU-23. The HDC/HDI catalyst may include a binder forthe molecular sieve, such as alumina, titania, silica, silica-alumina,zirconia, or a combination thereof, for example alumina and titania orsilica and zirconia, titania, or both.

In various examples, the catalysts according to the disclosure furtherinclude a hydrogenation catalyst to saturate multiple bonds andaromatics, which may be termed hydrofinishing herein. The hydrogenationcatalyst typically includes a metal hydrogenation component that is aGroup VI and/or a Group VIII metal. In some examples, the metalhydrogenation component is a Group VIII noble metal. For example, themetal hydrogenation component may be Pt, Pd, or a mixture thereof.Further, the metal hydrogenation component may be a combination of anon-noble Group VIII metal with a Group VI metal. Suitable combinationscan include Ni, Co, or Fe with Mo or W, or, in some examples, Ni with Moor W.

The metal hydrogenation component may be added to the catalyst in anyconvenient manner. For example, the metal hydrogenation component may becombined with the catalyst using an incipient wetness. In thistechnique, after combining a zeolite and a binder, the combined zeoliteand binder can be extruded into catalyst particles. These catalystparticles may then be exposed to a solution containing a suitable metalprecursor. In some examples, metal can be added to the catalyst by ionexchange, where a metal precursor is added to a mixture of zeolite (orzeolite and binder) prior to extrusion.

The amount of metal in the catalyst may be at least about 0.1 wt. %based on catalyst, or at least about 0.15 wt. %, or at least about 0.2wt. %, or at least about 0.25 wt. %, or at least about 0.3 wt. %, or atleast about 0.5 wt. % based on catalyst. The amount of metal in thecatalyst may be about 20 wt. % or less based on catalyst, or about 10wt. % or less, or about 5 wt. % or less, or about 2.5 wt. % or less, orabout 1 wt. % or less. For examples where the metal is Pt, Pd, anotherGroup VIII noble metal, or a combination thereof, the amount of metalmay be from about 0.1 to about 5 wt. %, about 0.1 to about 2 wt. %, orabout 0.25 to about 1.8 wt. %, or about 0.4 to about 1.5 wt. %. Forexamples where the metal is a combination of a non-noble Group VIIImetal with a Group VI metal, the combined amount of metal may be fromabout 0.5 wt. % to about 20 wt. %, or about 1 wt. % to about 15 wt. %,or about 2.5 wt. % to about 10 wt. %.

A zeolite can be combined with binder in any convenient manner. Forexample, a bound catalyst can be produced by starting with powders ofboth the zeolite and binder, combining and mulling the powders withadded water to form a mixture, and then extruding the mixture to producea bound catalyst of a desired size. Extrusion aids can also be used tomodify the extrusion flow properties of the zeolite and binder mixture.

Process conditions in a catalytic HDC/HDI zone in a may include atemperature of from about 200 to about 450° C., or from about 270 toabout 400° C., a hydrogen partial pressure of from about 1.8 MPag toabout 34.6 MPag (about 250 psig to about 5000 psig), or from about 4.8MPag to about 20.8 MPag, and a hydrogen circulation rate of from about35.6 m³/m³ (200 SCF/B) to about 1781 m³/m³ (10,000 SCF/B), or from about178 m³/m³ (1000 SCF/B) to about 890.6 m³/m³ (5000 SCF/B). In otherexamples, the conditions can include temperatures in the range of about600° F. (343° C.) to about 815° F. (435° C.), hydrogen partial pressuresof from about 500 psig to about 3000 psig (3.5 MPag-20.9 MPag), andhydrogen treat gas rates of from about 213 m³/m³ to about 1068 m³/m³(1200 SCF/B to 6000 SCF/B). These latter conditions may be suitable, forexample, if the HDC/HDI stage is operating under sour conditions, e.g.,in the presence of high concentrations of sulfur compounds.

The liquid hourly space velocity (LHSV) can vary depending on the ratioof hydrocracking catalyst used to hydroisomerization catalyst in theHDC/HDI catalyst. Relative to the combined amount of hydrocracking andhydroisomerization catalyst, the LHSV may be from about 0.2 h⁻¹ to about10 h⁻¹ such as from about 0.5 h⁻¹ to about 5 h⁻¹ and/or from about 1 h⁻¹to about 4 h⁻¹ Depending on the ratio of hydrocracking catalyst tohydroisomerization catalyst used, the LHSV relative to only the HDC/HDIcatalyst can be from about 0.25 h⁻¹ to about 50 h⁻¹ such as from about0.5 h⁻¹ to about 20 h⁻¹ or from about 1.0 h⁻¹ to about 4.0 h⁻¹.

Hydro-Finishing and Aromatic Saturation Process

In some examples, a hydrofinishing stage, an aromatic saturation stage,or both may be used. These stages are termed finishing processes herein.Finishing processes may improve color and stability in a final productby lowering the amounts of unsaturated or oxygenated compounds in thefinal product streams. The finishing may be performed in thehydro-processing reactor 126 after the last hydrocracking orhydroisomerization stage. Further, the finishing may occur afterfractionation of a hydro-processed stream 128 in a product distillationcolumn 132. If finishing occurs after fractionation, the finishing maybe performed on one or more portions of the fractionated product, suchas being performed on the heavy neutral stream 134 from the to productdistillation column 132. In some examples, the entire effluent from thelast hydrocracking or HDC/HDI process can be finished prior tofractionation into individual product streams.

In some situations, the finishing processes, including hydrofinishingand aromatic saturation, may refer to a single process performed usingthe same catalyst. Alternatively, one type of catalyst or catalystsystem can be provided to perform aromatic saturation, while a secondcatalyst or catalyst system can be used for hydrofinishing. Typicallythe finishing processes will be performed in a separate reactor from theHDC/HDI or hydrocracking processes to facilitate the use of a lowertemperature for the finishing processes. However, an additionalhydrofinishing reactor following a hydrocracking or HDC/HDI process, butprior to fractionation, may still be considered part of a second stageof a reaction system conceptually.

Finishing catalysts can include catalysts containing Group VI metals,Group VIII metals, and mixtures thereof. In an example, the metals mayinclude a metal sulfide compound having a strong hydrogenation function.The finishing catalysts may include a Group VIII noble metal, such asPt, Pd, or a combination thereof. The mixture of metals may also bepresent as bulk metal catalysts wherein the amount of metal is 30 wt. %or greater based on the catalyst. The metals and metal compounds may besupported, for example, on a metal oxide. Suitable metal oxide supportsinclude low acidic oxides such as silica, alumina, silica-aluminas ortitanic, or, in some examples, alumina.

The catalysts for aromatic saturation may include at least one metalhaving relatively strong hydrogenation function on a porous support.Typical support materials include amorphous or crystalline oxidematerials such as alumina, silica, and silica-alumina. The supportmaterials may also be modified, such as by halogenation or fluorination.The metal content of the catalyst may be as high as 20 wt. % fornon-noble metals. In an example, a hydrofinishing catalyst is acrystalline material belonging to the M41S class or family of catalysts.The M41S family of catalysts are mesoporous materials having high silicacontent. Examples include MCM-41, MCM-48 and MCM-50. If separatecatalysts are used for aromatic saturation and hydrofinishing, anaromatic saturation catalyst can be selected based on activity orselectivity for aromatic saturation, while a hydrofinishing catalyst canbe selected based on activity for improving product specifications, suchas product color and polynuclear aromatic reduction.

Finishing conditions can include temperatures from about 125° C. toabout 425° C., or about 180° C. to about 280° C., a hydrogen partialpressure from about 500 psig (3.4 MPa) to about 3000 psig (20.7 MPa), orabout 1500 psig (10.3 MPa) to about 2500 psig (17.2 MPa), and an LHSVfrom about 0.1 hr⁻¹ to about 5 hr⁻¹ LHSV, or, in some examples, 0.5 hr⁻¹to 1.5 hr⁻¹ Additionally, a hydrogen treat gas rate of from about 35.6m³/m³ to about 1781 m³/m³ (200 SCF/B to 10,000 SCF/B) can be used.

Fractionation and Products

After hydro-processing, the hydro-processed oligomers in thehydro-processed stream 130 can be fractionated in the productdistillation column 132. Any number of fractions may be isolated,including, for example, a distillate stream 136 that may includenaphtha, diesel, or a distillate fuel fraction, among others. Fractionsthat form hydrocarbon fluids for lubricants and other hydrocarbonproducts, may be isolated, including, for example, a light neutralstream 138, and a medium neutral stream 140, in addition to the heavyneutral stream 134, as described herein.

A bottoms stream 142 may also be isolated. In some examples, the bottomsstream 142 may be returned to the hydro-processing reactor 126 forfurther processing. Further, the bottoms stream 142 may be returned tothe cracker 104, for example, by being blended with the lighthydrocarbon stream 102, increasing the yield of the raw product stream106.

To form product streams, such as diesel fluid, naphtha, and gasoline,the intermediate olefinic stream 122 may be combined with the distillatestream 136 to form a combined stream 144 and further processed. In someexamples, the combined stream 144 is hydro-processed, then distilled toform the product streams. This may be performed in a productisomerization reactor 146, for example, using the process describedherein, to hydroisomerize the combined stream 144, to hydrogenate thecombine stream 144, or to perform other hydro-processing reactions. Thehydro-processed product stream 148 may be provided to a productdistillation column 150 for the separation of hydrocarbon fluids, suchas a diesel fuel stream 152, a gasoline stream 154, and a lighthydrocarbon fluid stream 156. In an example, the light hydrocarbon fluidstream 156 includes isomers of C5 to C7 compounds. An overhead stream158 may include very light hydrocarbons or gases, such as propane andbutane. A heavy product stream 160 may be returned to the productisomerization reactor 146. In some examples, the heavy product stream160, the overhead stream 158, or both, are returned to the steamcracking reactor 104.

Method for Producing Hydrocarbon Fluids from Light Hydrocarbon Streams

FIG. 2 is a process flow diagram of a method 200 for producinghydrocarbon fluids from a light hydrocarbon stream, in accordance withexamples. The method 200 may be implemented using the equipment andconditions described with respect to FIG. 1. The method begins at block202 when a light hydrocarbon is cracked to form a raw product stream.This may be performed by contacting the light hydrocarbon stream withsteam and a heterogeneous catalyst. Naphtha, steam cracking gas oil(SCGO), or tar, among others, may be separated from the raw productstream, for example, in a quench tower. Further, hydrogen sulfide,carbon dioxide, or both, may be separated from the raw product stream,for example, using a caustic tower or an amine separator.

At block 204, water is removed from the raw product stream to form anoligomerization feed stream. As described herein, this may be performedusing a condenser, a cold box, a molecular sieve tower, and the like.

At block 206, the oligomerization feed stream is oligomerized to form anintermediate stream. As described herein, this may be performed bycontacting the oligomerization feed stream with a heterogeneous catalystincluding a zeolite on a metal oxide support. The composition of theintermediate stream may be controlled by changing a ratio of the zeoliteto the metal oxide support. A light olefinic stream may be distilledfrom the intermediate stream. Further, a heavy olefinic stream may bedistilled from the intermediate stream.

At block 208, a heavy olefinic stream is distilled from the intermediatestream. At block 210, the heavy olefinic stream is hydro-processed toform a hydro-processed stream. In the hydro-processing, the heavyolefinic stream may be hydrocracked to form lower molecular weightcompounds, for example, having a broader distribution. The heavyolefinic stream may be hydroisomerized to form a distribution ofdifferent isomers. Further, the heavy olefinic stream may be finished todecrease unsaturated and aromatic compounds in the hydro-processedstream. In some examples, an intermediate olefinic stream is isolatedfrom the intermediate stream and combined with the heavy olefinic streamfor hydro-processing.

At block 212, the hydro-processed stream is distilled to form a numberof hydrocarbon fluids. Distilling the hydro-processed stream may includeseparating a distillate stream, a naphtha stream, or both from thehydro-processed stream. In some examples, the distillate stream iscombined with the intermediate olefinic stream and processed to formfinal products, such as diesel fuel, gasoline, light lubricants, andother hydrocarbon fluids. Further, distilling the hydro-processed streammay include forming a heavy neutral oil stock stream, a medium neutraloil stock stream, or a light neutral oil stock stream, or anycombinations thereof.

EXAMPLES Analysis Techniques

The gas chromatography analysis of compositions described herein wasperformed using a method to enable coverage up to C30. The column was 30m long, with an inner diameter of 0.32 millimeters and a packing of 0.25μm, available as a HP-5 column from Agilent. The carrier gas wasnitrogen. The injector was held at a temperature of 150° C. and 10 psi.A 50 to 1 split ratio was used with a 121 mL per minute (mL/min) totalflow rate and an injection size of 1-5 μL. The column oven was set to a50° C. initial temp with a 10° C./min ramp rate to a 320° C. finaltemperature. It was held at the 320° C. temperature for 8 minutes givinga total run time of 35 minutes. The detector was a flame ionizationdetector held at 300° C., using a 30 mL/min flow of hydrogen, a 250mL/min flow of air, and a 25 mL/min makeup stream of nitrogen. The gaschromatography analysis for dimerization or alkylation products wasperformed using a high temperature method to enable coverage up to C100.The column was 6 m long, with an inner diameter of 0.53 millimeters anda packing of 0.15 μm, available as a MXT-1 SimDist column from Restekcompany of State College, Pa. The carrier gas was nitrogen. The injectorwas held at a temperature of 300° C. and 0.9 psi. A 15 to 1 split ratiowas used with a 27.4 mL per minute (mL/min) total flow rate and aninjection size of 1 μL. The column oven was set to an 80° C. initialtemp with a 15° C./min ramp rate to a 400° C. final temperature. It washeld at the 400° C. temperature for 15 minutes giving a total run timeof 36.3 minutes. The detector was a flame ionization detector held at300° C., using a 40 mL/min flow of hydrogen, a 200 mL/min flow of air,and a 45 mL/min makeup stream of nitrogen.

The C-13 NMR analysis was performed using a Bruker 400 MHz Advance IIIspectrophotometer. The samples were dissolved in chloroform-D (CDCl₃) ortoluene-D8 in a 5 mm NMR tube at concentrations of between 10 to 15 wt.% prior to being inserted into the spectrophotometer. The C-13 NMR datawas collected at room temperature (20° C.). The spectra were acquiredwith time averaging to provide a signal to noise level adequate tomeasure the signals of interest. Prior to data analysis, spectra werereferenced by setting the chemical shift of the CDCl₃ solvent signal to77.0 ppm.

H-1 NMR data was collected at room temperature. The data was recordedusing a maximum pulse width of 45 degree, 8 seconds between pulses andsignal averaging of 120 transients.

Simulated distillation (SimDist) was run using the techniques describedin ASTM D2887-16a “Standard Test Method for Boiling Range Distributionof Petroleum Fractions by Gas Chromatography.” The equipment used isfurther described herein with respect to the Gas Chromatographyanalyses.

Example 1 Composition of Oligomerization Feed Stream After SimpleSeparation

An example of the weight and volumetric composition of a oligomerizationfeed stream composition formed in the steam cracking of ethane, afterseparation with a primary fractionator, a caustic tower, and a drier, isshown in Table 1. This composition was determined by gas chromatography.

TABLE 1 Oligomerization feed stream composition after simple separation:Volume (%) Hydrogen 44.2 Methane 6.37 Acetylene 1.19 Ethylene 36.4Ethane 11.4 Propylene 0.48 Carbon Monoxide 0.03

Example 2 Synthesis of the Heterogeneous Catalyst Material

Catalysts containing from about 10 parts to about 90 parts of a zeolyticcomponent and from about 90 parts to about 10 parts of a binder werecombined on a calcined dry weight basis. The zeolytic component andbinder dry powder was placed in a muller or a mixer and mixed for about10 to 30 minutes. Sufficient water was added to the components duringthe mixing process to produce an extrudable paste. The extrudable pastewas formed into a quadralobe or cylinder extrudate using an extruder.After extrusion, the extrudate was dried at a temperature ranging fromabout 250° F. to about 325° F. (168° C.). After drying, the driedextrudate was heated to about 1000° F. (538° C.) under flowing nitrogen.The extrudate was then cooled to ambient temperature and humidified withsaturated air or steam. After the humidification, the extrudate was ionexchanged with about 0.5 to about 1 N ammonium nitrate solution. Theammonium nitrate solution ion exchange was repeated. The ammoniumnitrate exchanged extrudate was then washed with deionized water toremove residual nitrate prior to calcination in air. After washing thewet extrudate, it was dried. The dried extrudate was then calcined for 3h in a nitrogen/air mixture to a temperature of about 1000° F. (538°C.).

These catalysts may be used for the oligomerization of theoligomerization feed stream, which may include poisons, such asacetylene and carbon monoxide, in addition to ethylene, propylene,hydrogen, methane, ethane, propane. The zeolitic component for thecatalysts can include ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-48, ZSM-50,ZSM-57, MCM-22, MCM-49, MCM-56, and numerous other zeolites. The bindermay be selected from the group consisting of alumina, silica, titania,zirconia, tungsten oxide, ceria, niobia and combinations thereof.

Example 3 Oligomerization Feed Stream Conversion to Higher MolecularWeight Products

The capability of the heterogeneous catalyst with a zeolytic componentto oligomerize the oligomerization feed stream was determined by testingthe material in a batch reactor. The test included loading a driedcatalyst into the reactor along with a liquid feed that could consist of100% alkane, such as decane or hexadecane, along with about 10 wt. % ofan olefin, such as pentene or decene. The ratio of feed to catalyst wasat a weight ratio of about 18 g/g. The reactor was inert purged withnitrogen while stirring. The ethylene oligomerization activity wasevaluated by adding a pressurized gas feed containing either ethylenealone or a combination of ethylene, propylene, hydrogen, methane,ethane, propane, acetylene, and carbon monoxide as described withrespect to Table 1. The mixture was then heated to between about 150° C.and about 250° C. while stirring for a designated amount of time, suchas 24 to 72 hours. In this example, the reaction was performed for 48hours. The reactor was run in semi-batch mode. The activity andselectivity was evaluated by analyzing the off-gas and liquid productcomposition.

FIG. 3 is a plot 300 of the yield of different weight molecules, showingthe changes as the catalyst is changed, in accordance with examples. Anexample reaction is the testing of 65% zeolite and 35% aluminaheterogeneous catalysts with a 10 wt. % decene/90 wt. % hexadecaneliquid feed at 225° C. and 200 psig total pressure for 48 hours with a100% ethylene gas feed. After subtraction of the hexadecane feed, thesimulated distillation by gas chromatography is shown in the plot ofFIG. 3, which shows that the yield of 580° F.⁺ (304° C.⁺) diesel rangemolecules as well as 710° F.⁺ (376° C.⁺) base stock range moleculesincreases as the catalyst is switched from ZSM-48 to ZSM-5 to ZSM-11.The increase in yield of 710° F. + (376° C.⁺) from below 30% for ZSM-5to above 35% for ZSM-11 is particularly surprising because the zeoliteshave similar Si:Al₂ ratios of 29:1 (ZSM-5) and 26:1 (ZSM-11). As shownin FIG. 3, the result from the simulated distillation by gaschromatography on a feed with no catalyst present shows little to noconversion.

Example 4 Hydrogen Impurity Effects on Oligomerization

A 65 wt. % ZSM-5 and 35 wt. % alumina heterogeneous catalyst was testedwith a 10 wt. % decene/90 wt. % hexadecane liquid feed at 200° C. and200 psig total pressure for 24 hours with one of two gas feeds, a 100vol. % ethylene feed and a 50 vol. % ethylene/50 vol. % hydrogen feed.After subtraction of the hexadecane feed, the simulated distillation bygas chromatography is shown in FIG. 4 for both gas feeds. There islittle to no difference in the product distribution between the 100%ethylene gas feed compared to the 50/50 ratio of ethylene to to hydrogenfeed. Accordingly, there is a significant economic incentive for notremoving the hydrogen.

Example 5 Carbon Monoxide and Acetylene Impurity Effects onOligomerization

FIG. 4 is a plot 400 of a simulated distillation by gas chromatographycomparing the products for a gas feed with hydrogen to a gas feedwithout hydrogen, in accordance with examples. A 65% ZSM-11 and 35%alumina heterogeneous catalyst was tested with a 10 wt. % decene/90 wt.% hexadecane liquid feed at 200° C. and 200 psig total pressure for 48hours with one of two gas feeds, a 100 vol. % ethylene feed, and a feedincluding 32.7 vol. % ethylene/50 vol. % hydrogen/10.6 vol. % ethane/6.1vol. % methane/0.5 vol. % propylene/0.1 vol. % carbon monoxide. Aftersubtraction of the hexadecane feed, the simulated distillation by gaschromatography is shown in the plot of FIG. 4 for both gas feeds. Thereis little to no difference in the product distribution between the 100%ethylene gas feeds versus the impure feed. Accordingly, there is asignificant economic incentive for not removing hydrogen and carbonmonoxide as it avoids having to compress to 550 psig and the use of thecold box.

Example 6 Product Characterization

The liquid product was analyzed by DEPT-135 C-13 NMR to furtherinvestigate the product characteristics. The DEPT-135 C-13 NMR of theproduct that boiled above 700° F. showed a significant amount ofbranching via the low concentration of epsilon-CH₂ aliphatic carbons orlinear methylenes in the product, as shown in further detail in Table 2.The branchiness is intrinsic to carbenium ion chemistry associated withBronsted acid site olefin oligomerization over zeolites. While theproduct has a low viscosity index (VI) when compared to conventionalbase stock and almost no wax, the highly branched high molecular weightmixture has value as a quality hydrocarbon fluid and diesel fuel.

In addition, the ZSM-11 catalyst had significantly less branched, ormore linear, products than ZSM-5 as indicated by the higherconcentration of linear methylenes at almost constant methylconcentration. This is a surprising result as both catalysts havesimilar Si:Al₂ ratios of 29:1 (ZSM-5) and 26:1 (ZSM-11) and have 10-ringopenings. The ZSM-11 has a slightly smaller openings, 5.3 Å×5.4 Å, atits widest, compared to the three dimensional ZSM-5's openings of 5.1Å×5.5 A and 5.3 Å×5.6 Å. This is described further in Table 2 along withexamples of the structural features.

FIGS. 5(A) and 5(B) are plots of C-13 NMR spectra comparing a testproduct to a hydrocarbon fluid. The NMR in FIG. 5(A) is of a hydrocarbonfluid solvent consisting of mostly paraffins. The NMR in FIG. 5(B) is ofa product made using a ZSM-5 oligomerization catalyst. The similaritiesindicate that boiling range cuts of the product may be useful ashydrocarbon fluids for industrial solvent applications.

FIGS. 6(A) to 6(C) are 1-H NMR spectra comparing test products to aGroup II hydrocarbon base stock. FIG. 6(A) is an NMR spectrum of theGroup II base stock. FIG. 6(B) is a product spectrum formed using aZSM-5 catalyst for oligomerization shows all the characteristic peaks ofa Group II lube. The lower epsilon-CH2 and higher CH3 may decrease coldflow properties (such as Viscosity Index) but show the potential forbase stock production. We also show a figure that shows a LN, MN, and HNlube base stock compared to the boiling point range of our ZSM-5 sample.All three materials could be produced from this material.

EMBODIMENTS

The embodiments of the present techniques include any combinations ofthe examples in the following numbered paragraphs.

1. A system for manufacturing a base stock from a light hydrocarbonstream, including a cracker configured to form a raw product stream fromthe light hydrocarbon stream, a separator configured to remove waterfrom the raw product stream forming an oligomerization feed stream, andan oligomerization reactor configured to increase a molecular weight ofthe oligomerization feed stream forming a raw oligomer stream. Thesystem also includes a distillation column configured to separate aheavy olefinic stream from the raw oligomer stream, a hydro-processingreactor configured to hydro-process the heavy olefinic stream to form ahydro-processed stream, and a product distillation column configured toseparate the hydro-processed stream to form the base stock.

2. The system of embodiment 1, wherein the light hydrocarbon streamincludes ethane, butane, propane, or naphtha, or any combinationsthereof.

3. The system of either of embodiments 1 or 2, wherein the crackerincludes a steam cracking reactor.

4. The system of any of embodiments 1 to 3, wherein the separatorincludes a quench fractionator.

5. The system of any of embodiments 1 to 4, including a primaryfractionator configured to remove tar and steam cracking gas oil (SCGO)from the raw product stream, a caustic tower configured to removehydrogen sulfide from the raw product stream, and a dryer configured toremove the water from the raw product stream.

6. The system of any of embodiments 1 to 5, wherein the oligomerizationreactor is configured to use a heterogeneous catalyst.

7. The system of embodiment 6, wherein the heterogeneous catalystincludes a zeolite bound to a metal oxide.

8. The system of any of embodiments 1 to 7, wherein the hydro-processingreactor includes a hydrocracking unit.

9. The system of any of embodiments 1 to 8, wherein the hydro-processingreactor includes a hydroisomerization unit.

10. The system of any of embodiments 1 to 9, wherein the productdistillation column is configured to separate from the hydro-processedstream a distillate stream including naphtha, diesel fuel, and gasoline.

11. The system of any of embodiments 1 to 10, wherein the productdistillation column is configured to separate from the hydro-processedstream a heavy neutral stream, a medium neutral stream, and a lightneutral stream.

12. A method for manufacturing a base stock from a light hydrocarbonstream, including cracking the light hydrocarbon stream to form a rawproduct stream, removing water from the raw product stream to form anoligomerization feed stream, and oligomerizing the oligomerization feedstream to form an intermediate stream. The method also includesdistilling a heavy olefinic stream from the intermediate stream,hydro-processing the heavy olefinic stream to form a hydro-processedstream, and distilling the hydro-processed stream to form the basestock.

13. The method of embodiment 12, including separating naphtha, steamcracking gas oil (SCGO), or tar, or any combinations thereof, from theraw product stream.

14. The method of either of embodiments 12 or 13, including separatinghydrogen sulfide from the raw product stream.

15. The method of any of embodiments 12 to 14, including separatingcarbon dioxide from the raw product stream.

16. The method of any of embodiments 12 to 15, wherein oligomerizing theoligomerization feed stream includes contacting the oligomerization feedstream with a heterogeneous catalyst including a zeolite bound with ametal oxide.

17. The method of embodiment 16, including controlling a composition ofthe intermediate stream by changing a ratio of the zeolite to a metaloxide binder.

18. The method of any of embodiments 12 to 17, including distilling alight linear alpha olefin stream from the intermediate stream.

19. The method of any of embodiments 12 to 18, including distilling aheavy linear alpha olefin stream from the intermediate stream.

20. The method of any of embodiments 12 to 19, wherein hydro-processingthe heavy olefinic stream includes hydrocracking the heavy olefinicstream.

21. The method of any of embodiments 12 to 20, wherein hydro-processingthe heavy olefinic stream includes hydroisomerizing the heavy olefinicstream.

22. The method of any of embodiments 12 to 21, wherein distilling thehydro-processed stream includes separating a distillate stream, anaphtha stream, or both from the hydro-processed stream.

23. The method of any of embodiments 12 to 22, wherein distilling thehydro-processed stream includes forming a heavy neutral oil stockstream, a medium neutral oil stock stream, or a light neutral oil stockstream, or any combinations thereof.

24. A system for manufacturing a base oil stock from a light hydrocarbonstream, including a steam cracker to form a raw product stream from thelight hydrocarbon stream, a separator configured to remove naphtha,water, steam cracker gas oil (SCGO), and tar from the raw product streamto form an oligomerization feed stream, and an oligomerization reactorconfigured to convert the oligomerization feed stream to a highermolecular weight stream by contacting the oligomerization feed streamwith a heterogeneous catalyst. The system also includes a distillationcolumn configured to separate a heavy olefinic stream from the highermolecular weight stream, wherein the distillation column is configuredto recover a light alpha-olefin stream from the higher molecular weightstream. A hydro-processing reactor is configured to demetallate theheavy olefinic stream, to crack the heavy olefinic stream, to formisomers in the heavy olefinic stream, or to hydrogenate olefinic bondsin the heavy olefinic stream, or any combinations thereof. A productdistillation column is configured to separate the isomers in the heavyolefinic stream to form a number of base stock streams.

25. The system of embodiment 24, wherein the light hydrocarbon streamincludes ethane.

26. The system of either of embodiments 24 or 25, wherein theheterogeneous catalyst includes a zeolite bound with alumina.

While the present techniques may be susceptible to various modificationsand alternative forms, the embodiments discussed above have been shownonly by way of example. However, it should again be understood that thetechniques is not intended to be limited to the particular embodimentsdisclosed herein. Indeed, the present techniques include allalternatives, modifications, and equivalents falling within the truespirit and scope of the appended claims.

1. A system for manufacturing a base stock from a light hydrocarbonstream, comprising: a cracker configured to form a raw product streamfrom the light hydrocarbon stream; a separator configured to removewater from the raw product stream forming an oligomerization feedstream; an oligomerization reactor configured to increase a molecularweight of the oligomerization feed stream forming a raw oligomer stream;a distillation column configured to separate a heavy olefinic streamfrom the raw oligomer stream; a hydro-processing reactor configured tohydro-process the heavy olefinic stream to form a hydro-processedstream; and a product distillation column configured to separate thehydro-processed stream to form the base stock.
 2. The system of claim 1,wherein the light hydrocarbon stream comprises ethane, butane, propane,or naphtha, or any combinations thereof.
 3. The system of claim 1,wherein the cracker comprises a steam cracking reactor.
 4. The system ofclaim 1, wherein the separator comprises a quench fractionator.
 5. Thesystem of claim 1, comprising: a primary fractionator configured toremove tar and steam cracking gas oil (SCGO) from the raw productstream; a caustic tower configured to remove hydrogen sulfide from theraw product stream; and a dryer configured to remove the water from theraw product stream.
 6. The system of claim 1, wherein theoligomerization reactor is configured to use a heterogeneous catalyst.7. The system of claim 6, wherein the heterogeneous catalyst comprises azeolite bound to a metal oxide.
 8. The system of claim 1, wherein thehydro-processing reactor comprises a hydrocracking unit.
 9. The systemof claim 1, wherein the hydro-processing reactor comprises ahydroisomerization unit.
 10. The system of claim 1, wherein the productdistillation column is configured to separate from the hydro-processedstream a distillate stream comprising naphtha, diesel fuel, andgasoline.
 11. The system of claim 1, wherein the product distillationcolumn is configured to separate from the hydro-processed stream: aheavy neutral stream; a medium neutral stream; and a light neutralstream.
 12. A method for manufacturing a base stock from a lighthydrocarbon stream, comprising: cracking the light hydrocarbon stream toform a raw product stream; removing water from the raw product stream toform an oligomerization feed stream; oligomerizing the oligomerizationfeed stream to form an intermediate stream; distilling a heavy olefinicstream from the intermediate stream; hydro-processing the heavy olefinicstream to form a hydro-processed stream; and distilling thehydro-processed stream to form the base stock.
 13. The method of claim12, comprising separating naphtha, steam cracking gas oil (SCGO), ortar, or any combinations thereof, from the raw product stream.
 14. Themethod of claim 12, comprising separating hydrogen sulfide from the rawproduct stream.
 15. The method of claim 12, comprising separating carbondioxide from the raw product stream.
 16. The method of claim 12, whereinoligomerizing the oligomerization feed stream comprises contacting theoligomerization feed stream with a heterogeneous catalyst comprising azeolite bound with a metal oxide.
 17. The method of claim 16, comprisingcontrolling a composition of the intermediate stream by changing a ratioof the zeolite to a metal oxide binder.
 18. The method of claim 12,comprising distilling a light linear alpha olefin stream from theintermediate stream.
 19. The method of claim 12, comprising distilling aheavy linear alpha olefin stream from the intermediate stream.
 20. Themethod of claim 12, wherein hydro-processing the heavy olefinic streamcomprises hydrocracking the heavy olefinic stream.
 21. The method ofclaim 12, wherein hydro-processing the heavy olefinic stream compriseshydroisomerizing the heavy olefinic stream.
 22. The method of claim 12,wherein distilling the hydro-processed stream comprises separating adistillate stream, a naphtha stream, or both from the hydro-processedstream.
 23. The method of claim 12, wherein distilling thehydro-processed stream comprises forming a heavy neutral oil stockstream, a medium neutral oil stock stream, or a light neutral oil stockstream, or any combinations thereof.
 24. A system for manufacturing abase oil stock from a light hydrocarbon stream, comprising: a steamcracker to form a raw product stream from the light hydrocarbon stream;a separator configured to remove naphtha, water, steam cracker gas oil(SCGO), and tar from the raw product stream to form an oligomerizationfeed stream; an oligomerization reactor configured to convert theoligomerization feed stream to a higher molecular weight stream bycontacting the oligomerization feed stream with a heterogeneouscatalyst; a distillation column configured to separate a heavy olefinicstream from the higher molecular weight stream; the distillation columnconfigured to recover a light alpha-olefin stream from the highermolecular weight stream; a hydro-processing reactor configured todemetallate the heavy olefinic stream, to crack the heavy olefinicstream, to form isomers in the heavy olefinic stream, or to hydrogenateolefinic bonds in the heavy olefinic stream, or any combinationsthereof; and a product distillation column to separate the isomers inthe heavy olefinic stream to form a plurality of base stock streams. 25.The system of claim 24, wherein the light hydrocarbon stream comprisesethane.
 26. The system of claim 24, wherein the heterogeneous catalystcomprises a zeolite bound with alumina.